Method of electric welding.



No. 645,066. Patented Mari l3, I900. B. P. snown &. r. E. MORSE.

METHOD OF ELECTRIC WELDING.

(Application filed Mar. 16, 1898.)

(N6 Mqdel.)

THE uonms PETERS co. puorouwm wns'riimmm o. c.

UNITED STATES PATENT OFFICE.

ROBERT P. BROWVN AND FRANKLIN E. MORSE, OF NEIV YORK, N. Y.

METHOD OF ELECTRIC WELDING.

SPECIFICATION forming part of Letters Patent No. 645,066, dated March13, 1906;

Application filed March 16, 1898- Serial N0. 674,002. (No specimens.)

To all whom, it may concern.-

Be it known that we, ROBERT P. BROWN and FRANKLIN E. MORSE, citizens ofthe United States, residing in the city of New York,borough of Brooklyn,county of Kings, and State of New York, have invented certain new anduseful Improvements in the Art of XVelding or Brazing, of which thefollowing is a specification.

Our invention relates to an improved method of producing welded orbrazed joints between metal pieces, and is particularly applicable wherethe parts to be united are in the form of comparatively-thin plates,strips, 850., which are fastened together flatwise and where the metalof one part has a higher temperature of fusion than the metal of theother part or where the parts being of the same temperature of fusionone part is thinner than the other-that is to say, where the metals tobe joined have diiferentcharacteristios. The difficulty in making such ajoint arises from the nature of the union and of the pieces to beunited. In many cases it is not practicable to heat the parts separatelyand afterward unite them,nor will the now-common method of buttweldingby electricity accomplish the end, although metals having diiferentcharacteristics are readily united in this way. If the parts are placedtogether in the position in which they are to be united and heat appliedto the joint in any of the ordinary ways, a proper union will not beaccomplished, inasmuch as the metal having the lower point of fusionwill become burned or melted before the other is brought to its requiredtemperature, or where the metals of the parts are the same and one partthinner than the other the thinner piece will reach the welding orbrazing point before the larger mass in the other part has attained therequisite temperature and will thereafter become injured, if notdestroyed, from excess of heat. Much more difficult still is it to unitethe parts when the one having the lower point of fusion is at the sametime thinner than the other.

The object of our improvement is therefore to provide a method by whichmetal pieces having different characteristics may be applied to eachother in the desired position and while thus in situ have heat appliedto them in such manner and degree as to bring the parts to theirrespective welding or brazing temperature at approximately the sametime.

To carry our invention into effect, we make use, preferably, of theelectric current, since by its means and the ease of its manipulation weare enabled most readily to apply the required amount of heat to therespective parts at the required difference in degree.

In the accompanying drawings we have shown by way of illustration twoways in which our method may be accomplished by,

electrical apparatus.

Figure 1 shows diagrammatically an apparatus intended for carrying outour process wherein the proper heating effects are secured by the use ofcarbons of different size, and Fig. 2 a similar view showing anapparatus intended for the carrying out of our process wherein theproper heating effects are secured by shunting one of the carbons.

In Fig. 1 the numerals 1 and 2 represent edge views of two flat piecesof metal which are to be united by a welded or brazed joint, (andhereinafter we shall only use the terms welded joint or welded, meaningthereby to include as well a brazed joint or brazed.) 1 is the thickerpiece or the metal having the higher temperature of fusion, and 2 thethinner piece or the one having the lower temperature of fusion.

3 and 4 are two electrodes, which are held in contact with the pieces 1and 2 by means of resilient metal arms 5 and 6, bolted to a block 7. Thearms 5 and 6 are connected by wires 8 and 9 to a dynamo or converter,and a switch 10 may be used to short-circuit said arms when desired. Thetwo pieces 1 and 2 being held together between the electrodes 3 and atby the elasticity of the resilient arms 5 and 6, the current will passacross the two metals at their juncture from electrode to electrode, thenovelty of our invention lying in the relative construction of theseelectrodes and in the manner of manipulating the electric currentpassing through them.

In the first place, in our preferred method we make the electrodes ofrefractory conducting material, such as compressed carbon, and of suchinternal resistance to the current that the electrodes themselves areheated to a high degree, especially at their surfaces which are incontact with the metals. The heat from the electrodes is thus impartedto the metals by conduction from the electrodes where they are incontact, and the resistance of the metals themselves tothe current isalso utilized in heating the same.

In order to accomplish the object in view, one of the electrodes-namely,that which is in contact with the thicker metal or the metal having thehigher temperature of fusion must be heated to a higher degree than theother, or, in other words, the two electrodes must impart to theiradjacent metals such relative amounts of heat that the two pieces shallarrive at their respective welding temperatures at approximately thesame time. One way to heat one electrode to a higher de gree than theother is to have that electrode present a greater resistance to thecurrent than the other, and this may be accomplished either by makingsaid electrode of less density than the other or of a different materialwhich presents a greater resistance or of a smaller cross-sectional areawhen the two are of the same material and density.

In the figure referred to we have shown one electrode 5 smaller than theother. Suppose I to be a plate of steel and 2 a plate of copper andthinner than 1. It is evident that if heat in equal intensity wereapplied to both sides of the joint the copper would be melted or burnedbefore the steel could be sufficiently heated; but by means of thedifference in the electrodes the heat is so applied to the parts thatthe steel will be brought up to the required temperature before thecopper can be injured, the copper being heated more slowly by the lowertemperature imparted to the larger electrode t. Experience will readilydetermine the relative construction of the electrodes necessary to dothe work under any given conditions as to size, shape, and differenceinthe metals of the pieces to be united. As soon as the parts are broughtto their relative requisite temperatures the current through theelectrodes is turned off, as by operating the short-circuiting switch10, and the joint is allowed to cool or set, after which the electrodes3 and 4 are removed. It will be found that the resulting joint will beclean and perfect.

In Fig. 2 we have shown a modified form of the apparatus, in which oneset of electrodes may be made to do the work under a great variety ofdifferent conditions. Here we have shown the electrodes 3 and 4. of thesame size, and they may be made of like materials and density. Theelectrode 3 will be in contact with a heavy bar 11 in the circuit, andthe electrode 4' will be engaged by and maintained in contact with thepiece 2 to retain the latter in its position upon the heavier piece 1 bya corresponding bar 12, also in the circuit. The bar 12 may, near itsrear end, rest upon the block 13, made, preferably, of carbon, so that apart of the current from the electrode 4t will be shunted through saidblock, whereby the electrode 4 may be maintained at the desired lowertemperature. By varying the pressure upon the carbon block 13 theresistance of the shunt will be varied, so that the amount of currenttending to heat the electrode 4 may be adjusted within the desiredlimits. We have described this simple form of regulator merely by way ofillustration. Other and more approved ways of accomplishing the sameresult will readily ap pear to the skilled electrician. This regulatormay also be applied to the form of apparatus shown in Fig. 1. With theapparatus shown in Fig. 2 a short-circuiting switch 14 may be employedto short-circuit the operating-current after the joint has beenfinished. Instead of effectingareduction in the temperature of theelectrode in contact with the metal having the lower temperature offusion or the smaller mass by using in contact with such metal anelectrode of larger area or of smaller resistance or by shunting aportion of the current from that electrode, as explained, it will bepossible to effect the same result by intermittently short-circu itin gthat electrode, whereby the requisite current may be conducted to thesame as to result in the proper heating thereof. \Vith an apparatus suchas shown in Fig. 2 this may be accomplished by dispensing with theshunting-block l3 and by intermittently engaging the rear end of the bar12 with the plate 1 or other work, so that when the said bar is incontact with the plate the electrode 4: will be short-circuited and nocurrent will affect the same. mittent short-circuitings of the electrodel may be relatively frequent, or,instead,the full current may be allowedto affect the said electrode for a considerable period of timesay for ahalf-minute or more-until the piece 2 has been raised to adangerously-high point, after which the said electrode may beshortcircuited until the piece 2 is slightly cooled, during which timeit will be understood the electrode 3 is being influenced by the entirecurrent and is bringing the larger piece 1 or that having alowertemperature of fusion up to the Welding or brazing temperature.

We propose to use a current of low voltage and high amperage, but donotlimit ourselves to this. The current may be either direct oralternating. By this means a joint of this nature is very quickly madeand presents a neat appearance when completed. The electrodes may beshaped in a variety of ways to accommodate many different conditions inthe nature of the work to be done. In fact much work can be readily andquickly done by this method which it is now very difficult, and even inmany instances impossible, to accomplish by means hitherto employed. Afield in which our method is particularly ap pli'cable and in which wehave operated the same with success is that of welding flatcopperbonding-strips directlyto the rails of electric railways.

With the use of the electrodes in the manner above described the heat islocalized im- The interinediately at the place of juncture, with therequired difference in degree upon the sides of the joint which isnecessary to bring the steel of the rail and the copper of thebonding-strip to their respective welding temperatures at the same time,and a perfect joint is very quickly and readily made.

iVhile describing our method as preferably carried out by means ofelectricity in the manner above set fort-h, we do not limit ourselves tothe precise instrumentalities described nor to electricity only as thesource of heat. The heat as applied in our method of procedure may bederived from other sources, such as oxyhydrogen or other gas flames, itbeing necessary to have such control over the heat sources on eitherside of the joint that the heat derived therefrom shall be concentratedupon the metals at the opposite sides of the joint and the respectiveheat intensi ties at the point of concentration varied as the nature ofthe metals may require.

What we claim as our invention, and desire to secure by Letters Patent,is=

1. The method of welding or brazing together flatwise metal pieces,having difier' ent characteristics, which consists in holding the piecestogether atthe seam or joint, and concentrating heat from two externalheat sources upon the metals at opposite sides of the joint, therelative thermal intensities at the point of concentration being soproportioned that the metals of the parts shall be brought to theirrespective welding or braz ing temperatures at approximately the sametime.

2. The method of welding or brazing together fiatwise metal pieces,having different characteristics, which consists in holding the piecestogether at the seam or joint between two electrodes, passing anelectric current from one electrode to the other across the joint, theelectrodes being so arranged and constructed that the current passingthrough them is made to impart different degrees of heat to the twoelectrodes, whereby the metal pieces at the joint are made to attaintheir respective welding or brazing temperatures by conduction of heatfrom the electrodes, substantially as described, and of maintainingpressure upon the pieces after the heating-cunrent is turned oif anduntil the joint is suffl ciently cooled.

3. The method of welding or brazing together metal pieces havingdifferent charac= teristics, which consists in holding the piecestogether at the seam or joint between two electrodes, and passing anelectric current from one electrode to the other across the joint,shunting a portion of the current through one of the pieces, around theother piece and one of the electrodes, whereby that electrode receivesless heating-current than the other, and of maintaining pressure uponthe pieces after the heating-current is turned off, and until the jointis sufficiently cooled.

4. The method of welding or brazing together metal pieces havingdifferent characteristics, which consists in holding the pieces togetherat the seam or joint between two electrodes, passing an electric currentfrom one electrode to the other across the joint, shunting a portion ofthe current through one of the pieces, around. the other piece, and oneof the electrodes, whereby that electrode receives less heating-currentthan the other, providing means for varying and regulating the amount ofcurrent passing through the shuntingcircuit, and of'maintaining pressureupon the pieces after the heating-current is turned off and until thejoint is sufficiently cooled.

This specification signed and witnessed this 14th day of March, 1898.

ROBERT P. BROWN; FRANKLIN E. MORSE.

Witnesses:

V. W. Wi'ciins, FRANKLIN J. SPAULDING.

